A Japanese study has found that people who keep the most teeth over the age of 60 are least likely to develop dementia. However, the chance of having dementia seems to increase along with the number of teeth lost after this age, say researchers.
Tracking Tooth Loss and Dementia
The study involved 1,566 Japanese adults who were dementia-free at the outset and then tracked for around 5 years between 2007 and 2012.
At the start of the study, they were placed into four categories, according to their number of teeth. This ranged from none of their own teeth to 20 or more.
Over an average of 5.3 years, 11.5% of the volunteers developed some type of dementia, including Alzheimer's disease and vascular dementia, which happens when part of the brain doesn’t get enough blood carrying the oxygen and nutrients it needs, causing the brain’s nerve cells to break down.
The researchers found that the odds of developing dementia rose by 62% for those with 10 to 19 remaining teeth, compared with those who had 20 or more of their original set of 32.
This extra risk rose to 81% for those who had between one and nine teeth left.
Tooth loss was linked to the development of Alzheimer's disease, but not vascular dementia, although the researchers point out that there were fewer cases of vascular dementia to draw data from.
Inflammation or Unhealthy Habits
As far as why tooth loss and dementia might be related, researchers say one possible explanation is that tooth decay and gum disease could trigger inflammation –- something that raises your chances of having Alzheimer's disease.
Also, tooth loss might reflect a general lack of care and healthy habits throughout a person's life, they say.
Finally, they say chewing may increase blood flow and boost oxygen levels in the blood, and people with few teeth might find this harder to do. Also, a lack of teeth might make it harder for people to eat healthily.
The authors of the study, published in the Journal of the American Geriatrics Society, conclude: "The findings emphasize the clinical importance of promoting and supporting opportunities for dental care and treatment, especially in terms of maintenance of teeth from an early age, for reducing the risk of dementia in later life."
Lowering the Odds of Dementia
"Understanding how lifestyle factors can affect our risk of developing dementia is important, as there may be simple changes we can make to reduce our risk,” says Rosa Sancho, head of research at Alzheimer’s Research UK.
"This study didn’t look at the mechanisms underlying the link between oral health and dementia, but some research suggests that gum disease can raise the level of inflammation in the body and may contribute to a person’s dementia risk. Research is increasingly focussing on how inflammation plays a role in dementia, and this knowledge will help to influence our understanding of the risk factors for the condition.
"Good dental care is an important part of a healthy lifestyle, but we do not know the extent to which it can affect our dementia risk,” Sancho says. “The current best evidence for reducing our risk of dementia is that what is good for the heart is good for the head. Not smoking, eating a healthy balanced diet, keeping physically active, drinking in moderation, keeping cholesterol and blood pressure in check, and maintaining a healthy weight are all ways we can reduce our risk of dementia."